What is the difference between a where clause and a having clause

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Hi........

Oues: Hello all of you now i am implement some sql query in our application but i am confused from What is the difference between a "where" clause and a "having" clause? please explain and give a example...

Satyapriya Nayak · Answer

Hi Manish HAVING clause: -Specifies a search condition for a group or an aggregate. HAVING can be used only with the SELECT statement. HAVING is typically used in a GROUP BY clause. When GROUP BY is not used HAVING behaves like a WHERE clause. Having Clause is basically used only with the GROUP BY function in a query. Ex:- Table Store_Information store_name Sales Date Los Angeles $1500 Jan-05-1999 San Diego $250 Jan-07-1999 Los Angeles $300 Jan-08-1999 Boston $700 Jan-08-1999 SELECT store_name SUM(sales) FROM Store_Information GROUP BY store_name HAVING SUM(sales) > 1500 Result: store_name SUM(Sales) Los Angeles $1800 WHERE Clause:- is applied to each row before they are part of the GROUP BY function in a query. Ex:- Table Store_Information store_name Sales Date Los Angeles $1500 Jan-05-1999 San Diego $250 Jan-07-1999 Los Angeles $300 Jan-08-1999 Boston $700 Jan-08-1999 SELECT store_name FROM Store_Information WHERE Sales > 1000 Result: store_name Los Angeles Thanks

Hemant Kumar · Answer

Though the HAVING clause specifies a condition that is similar to the purpose of a WHERE clause the two clauses are not interchangeable. Listed below are some differences to help distinguish between the two: 1. The WHERE clause specifies the criteria which individual records must meet to be selcted by a query. It can be used without the GROUP BY clause. The HAVING clause cannot be used without the GROUP BY clause. 2. The WHERE clause selects rows before grouping. The HAVING clause selects rows after grouping. 3. The WHERE clause cannot contain aggregate functions. The HAVING clause can contain aggregate functions. http://www.geekinterview.com/question_details/16731